P912XDP512F0MFVR datasheet(505/1350 Pages) FREESCALE

部件名	P912XDP512F0MFVR

功能描述	Covers, S12XD, S12XB & S12XA Families

PDF	1350 Pages

Scroll/Zoom	100%

制造商	FREESCALE [Freescale Semiconductor, Inc]

网页	http://www.freescale.com

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505 / 1350 page

Chapter 11 Serial Communication Interface (S12SCIV5)

MC9S12XDP512 Data Sheet, Rev. 2.17

Freescale Semiconductor

505

In Figure 11-22 the veriﬁcation samples RT3 and RT5 determine that the ﬁrst low detected was noise and

not the beginning of a start bit. The RT clock is reset and the start bit search begins again. The noise ﬂag

is not set because the noise occurred before the start bit was found.

Figure 11-22. Start Bit Search Example 1

In Figure 11-23, veriﬁcation sample at RT3 is high. The RT3 sample sets the noise ﬂag. Although the

perceived bit time is misaligned, the data samples RT8, RT9, and RT10 are within the bit time and data

recovery is successful.

Figure 11-23. Start Bit Search Example 2

Reset RT Clock

Samples

RT Clock

RT Clock Count

Start Bit

RXD

LSB

Reset RT Clock

Samples

RT Clock

RT Clock Count

Actual Start Bit

RXD

LSB

Perceived Start Bit

P912XDP512F0MFVR 数据表(PDF) 505 Page - Freescale Semiconductor, Inc